Tension controlled winding apparatus



April 30, 1963 J. L. BALDWIN. JR.. ETAL 3,380,681

TENSION CONTROLLED WINDING APPARATUS Filed Feb. 16, 1966 2 Sheets-Sheet 1 POSITION A FIG. I

/1 9 INVENTOR,

JOHN L. BALDWIN ET AL ATTORNEYS J. L. BALDWIN. JR.. ETAL 3,380,681

TENSION CONTROLLED WINDING APPARATUS 2 Sheets-Sheet 2 KIN JOmPZOO muiom HIIII mOFOS Macy-Oh whsomimmhz ZO H mm mm INVENTOR,

ATTO R N EYS JOHN L. BALDWIN ETAL coho;- uDOmOF mksomixmh A ril 30, 1968 Filed Feb. 16, 1966 United States Patent 3,380,681 TENSION CONTROLLED WINDING APPARATUS John L. Baldwin, Jr., Bethesda, and Donald E. Reed, Kensington, Md., and Ralph E. Walker, Washington, D.C., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army Filed Feb. 16, 1966, Ser. No. 529,185 7 Claims. (Cl. 242-5512) ABSTRACT OF THE DISCLOSURE An apparatus for handling filament or tape elements that are to be wound on reels wherein a desired maximum tension is simply controlled. This result is achieved through the use of individually electrically actuated torque clutches for each of the two reels on which the tape is to be stored with a further provision for a oneway overriding clutch intermediate each driving motor and its associated torque clutch.

Background of invention This invention relates to improvements in apparatus for handling filament or tape elements that are to be wound on reels or spindles wherein it is necessary or desirable that the maximum tension to which the filament or tape is subjected to be simply controlled.

This invention, while adaptable to all types of winding and reeling devices, has special utility in the handling of magnetic recording tapes.

In prior art handling apparatus, the arrangements for controlling tape tension have either been mechanically crude, or of such a degree of complexity as to create separate reliability and maintenance problems.

An important objective of the present invention is to improve the tension regulation and the ease of control of tape-handling apparatus without sacrificing economic feasibility.

Summary of invention In accordance with an illustrative embodiment of the invention, the foregoing objective is achieved through the use of individually electrically actuated torque clutches for each of the two reels on which the tape is to be stored, and the provision of one-way overriding clutches intermediate each driving motor and its associated torque clutch.

Brief description of the drawings The novel features characteristic of the invention, both as to its organization and method of operation, together with further objects and the advantages thereof will be better understood from the following description considered in connection with the accompanying drawings in which an illustrative embodiment of the invention is disclosed by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and do not define the limitations of the invention.

In the drawings:

FIG. 1 is a partially diagrammatic front elevational view of the apparatus of the present invention; and

FIG. 2 is a partially diagrammatic top plan view of the apparatus of FIG. 1, conventional portions thereof being omitted for clarity of illustration.

Description of invention With reference to the drawings, FIGS. 1 and 2 show a tape handling apparatus which, together with conventional electrical controls and switching, is adapted to permit the operation of the apparatus in any one of the follOWing modes: record, playback, record and playback, fast forward (wind) and fast reverse (rewind). The tension in the tape is controlled at all times, and therefore can never exceed the safe values which are inherent for the type of tape being used. Further, the tape may be braked from any mode of operation to stop, with no subsequent creep, and with the tape tension controlled.

Referring further to FIG. 1, the essential elements of the winding and reeling portion of a tape transport system are shown, the conventional portions associated therewith being shown somewhat diagrammatically.

The tape 1 is stored on a supply reel 2 from which it is to be wound onto a take-up reel 3, after passing conventional elements such as guide post 4, erase head 5, guide roller 6, record head 7, vertical guide 8, play head 9, capstan 10. Guide roller 6 and pinch roller 11 are mechanically mounted in such a manner as to be movable from the position A shown in FIG. 1 to the position B shown in FIG. 1. It will be clear that when these elements are in the position A the tape passes over heads 5, 7, and 9 and is pinched between elements 10 and 11, and that when these elements are moved to the position B that the tape bears against guide post 4, guide roller 6, and capstan 10, and does not touch the heads 5, 7, and 9.

Any convenient means may be used to mount rollers 6 and 11 for movement between these two positions. Mounting shaft 12 pivotally mounted on pivotal control means 13 is shown to illustrate one means for providing these two alternative roller positions. Control means 13 may conventional be operated by a switch 14 to place rollers 6 and 11 in the desired operative position. Referring further to FIGS. 1 and 2, the operative portions of the tape transport system are mounted in a conventional manner on housing front panel 15 or housing bottom panel 16 which form the supporting housing. A speed control dial and indicator 17 is mounted on housing front panel 15 between reels 2 and 3.

Referring now to FIG. 2, the essential elements of applicants tape transport system are shown, with the conventional portions being omitted for clarity of illustration. The novel operation of applicants winding and reeling system is due to the provision of certain elements correlated as shown in FIG. 2 or in a functionally equivalent manner. It will be understood that the following elements shown diagrammatically are conventional and may be conveniently mounted on and operated from front panel 15: AC. power sources 36, 36', 39, 42 and 42'; offon switches 37, 37', 40, 44, and 44; and power control means '43 and 43'. A synchronous capstan drive motor 18 operating at constant speed and a variable ratio transmission 20 are mounted on bottom panel 16. A drive shaft 19 extends from motor 18 to transmission 20 to provide the driving power for capstan drive shaft 21 which extends from transmission 20 through panel 15 and has capstan 10 mounted at the end thereof. Transmission 20 has another shaft with a ratio selector sprocket 22 mounted thereon. Sprocket 22 is connected to a sprocket 23 extending from speed control means 24 by a connector or chain 25 to transmit the control ratio from the speed control dial 17 to the variable ratio transmission 20 and thereby instantaneously control the capstan drive speed. Speed control means 24 is mounted on panel 15 with the dial and indicator portion 17 extending therethrough.

Referring further to FIG. 2, supply reel 2 is mounted on a shaft 26 by any conventional means, such as screw 27. Shaft 26 extends through panel 15, hearing 28, and spacer 29 and terminates at the inner end in a variable torque clutch 30. Variable torque clutch 30 is mounted 0n panel 16 and has another shaft 31 extending from the side opposite to shaft 26 and in line therewith. Shaft 31 is the drive shaft of torque motor 32 which is also mounted on panel 16. Shaft 31 may conveniently terminate in a bearing 33 mounted on panel 16. Intermediate torque motor 32 and variable torque clutch 3G, a one-way or over-running sprag clutch 34 is mounted on panel 16. Further, torque motor 32 will produce torque to turn reel 2 only in the clockwise direction as viewed in FIG. 1 and sprag clutch 34 will permit shaft 31 to rotate only in the same direction. All references to direction of rotation will be oriented with respect to the apparatus as viewed in FIG. 1. Torque motor 32 is connected to a conventional electrical circuit represented by elements 36 and 37 to selectively control the energization thereof, and variable torque clutch 30 is connected to a conventional electrical control circuit represented by elements 42, 43, and 44 to control the current supplied thereto, and thereby control the torque transmissable therethrough between shafts 31 and 26. Elements 26', 27', 28', 29, 3t), 31', 32, 33' and 34, operatively associated with take-up reel 3, perform functions analogous to elements 26, 27, 28, 29, 30, 31, 32, 33 and 34 with the following exceptions; torque motor 32' produces torque opposite to that of torque motor 32 and sprag clutch 34 will permit shaft 31' to rotate only in the direction opposite to shaft 31. Elements 20, 24, 3t 32 and 34 are all conventional elements readily commercially available. However, inasmuch as their combination provides novel utility when they are combined as disclosed by applicants, they will be further described.

Variable ratio transmission is a ball and disc integrator, a purely mechanical device normally used to obtain the integration of one variable with respect to others. Element 20 comprises an input disc driven at a constant speed through shaft 19 by capstan drive motor 18, two balls positioned one above another in a movable carriage positioned and controlled by ratio selector sprocket 22 and an output cylinder which is driven by these balls. This cylinder is connected to shaft 21 to drive capstan 10, the rotational speed thereof being proportional to the distance of the balls from the center of the disc. Speed control means 24 is a purely mechanical device comprising a series of gear trains directly connected to numerical indicators to give a number reading from one to one thousand on the speed control dial and indicator 17, the rotary dial portion thereof being adjustable to control sprocket 23 connected to sprocket 22 by connector 25 which may conveniently be a chain. It is now clear that a numerical dial setting on dial and indicator 17 will correspond to every speed of capstan 10 within the limits of the range of the apparatus, and that the speed of the tape can be instantly and continuously varied during the operation of applicants apparatus. Motor 32 is a conventional torque motor whose function is to operate under locked conditions to create a predetermined torque or tension which is applied to shaft 31. Surrounding shaft 31 is an over-running or sprag clutch 34 that permits shaft 31 to rotate freely in one direction and prevents rotation in the opposite direction. One end of shaft 31 extends into variable torque clutch of the hysteresis type. Clutch 3% consists of an input member connected to shaft 31 and an output member connected to shaft 26. These input and output members have no direct physical contact with each other, the clutching actions being wholly through magnetic attraction between these two members, and controlled by the application of predetermined values of electrical current thereto, all as is well known in the prior art.

The various methods of operation of the tape transport will now be described:

I. Shuttle modes (A) Fast forward (wind). Motor 32 is energized and rotates in the counter clockwise direction as viewed from the front panel of FIG. 1. Clutch 34 is over-running and shaft 31 is rotating. Electrical current into clutch 30' is controlled to a predetermined value that represents the maximum permissible torque desired at the reel 3. Pinch roller 11 and guide roller 6 are positioned in the position B shown in FIG. 1 which positions tape 1 to move past heads 5, 7 and 3 without contact and past capstan 10 and pinch roller 11 without restraint. The current to clutch 30 is controlled to provide a low value of torque upon shaft 26 and reel 2. The tape 1 is thus free to roll upon reel 3 limited only by the inertia of the rotating components 32', 34', 31', 30', 3, 2, 26 and 30, by frictional losses, and by the torque-speed characteristics of motor 32', and by the low torque in clutch 30.

(B) Fast reverse (rewind). This mode is similar to the wind mode in that the motor 32 is energized and rotates in a clockwise direction. Electrical current into the clutch 30 is controlled to provide the desired torque at reel 2 through shaft 26. The current to clutch 30' is controlled to provide a low value of torque upon shaft 26' and reel 3. Again the tape is free to reel in the opposite direction limited only by the analogous inertia, friction, and torque motor characteristics of the system as discussed for the wind mode.

II. Braking modes (A) Both clutches. The braking mode is the same regardless of the previous mode (play, record, or shuttle). Pinch roller 11 is positioned in the position B as shown in FIG. 1, and the values of current into both clutches 3t) and 36 are increased to the value corresponding to the maximum torque that can be applied to tape 1 without damage thereto. Whichever reel 2 or 3 that had previously been unreeling is thus connected through its associated clutch 30 or 30 to the shaft 31 or 31 rotating within sprag clutch 34 or 34'. Since both sprag clutches 34 and 34 are designed so as to prevent rotation of their associated shafts 31 and 31' in the unwinding direction (clockwise for 3 and 31' and counter clockwise for 2 and 31) the further movement of tape 1 is restrained and the motion of tape 1 will be stopped. The elapsed time of braking is a function of the inertia of the moving parts of the system and the torque created in whichever clutch 30 or St) is acting as the braking means.

(B) Single clutch. The braking action may also be performed by supplying current only to whichever clutch 30 or 31' is unwinding. By this method, the inertia of one torque motor 32 or 32' and its associated shaft 31 or 31 would be removed from the system.

It is therefore seen that moving tape 1 can be braked quickly to a stop from any operating mode without exceeding the allowable tensile limits of tape 1.

III. Play, record and record-playback The tape handling is identical for each of these three modes. Torque motor 32' is energized; shaft 31' rotates in a counter clockwise direction; and current is supplied to clutch 30' to a moderate value, usually selected to be slightly greater than the torque of motor 32'. Reel 3 thus rotates counter clockwise and winds the tape 1 thereon. Guide roller 6 and pinch roller 11 are positioned in the position A as shown in FIG. 1, constraining tape 1 against capstan 10 and permitting tape 1 to contact heads 5, 7 and 9. The tape 1 is thus caused to move from left to right as viewed in FIG. 1, moving at a rate determined by the peripheral speed of capstan 10, which is controlled by speed control means 24 through the setting of dial and indicator 17. Current of a predetermined value is supplied to clutch 30 and the tape 1 is pulled by the action of capstan 10 and pinch roller 11 while at the same time being restricted by the torque of clutch 30, thereby creating a predetermined tension in the tape 1 and cansing tape 1 to remain in close contact with the operative surface of each of heads 5, 7 and 9. Torque motor 32 is effectively isolated from the tape 1 by the low torque value of clutch 30, and the sytsem may be operated without motor 32 being energized.

Thus it is clear that applicants have disclosed a novel tension controlled winding apparatus which has special utility in the operation of systems requiring the control of the maximum tension in the medium being wound; which is easily switched between modes; and which provides for continuous speed control during operation while maintaining the essential function of tension control.

What is claimed is:

1. A recording medium drive comprising first and second spaced reels, record and playback heads situated between said reels, a recording tape extending between and being windable upon each of said reels, a tape drive capstan adjacent one of said heads, means for selectively pressing said tape into driving engagement with said capstan and thereby causing it to be drawn over said heads or for disengaging said tape from said heads and allowing it to slide freely over said capstan, first and second variable torque clutches, each having an input and an output shaft, said output shafts being respectively connected to said first and second reels, electrical power control means connected to each of said clutches for controlling the amount of torque to be connected between said input and output shafts, first drive means connected to said first clutch input shaft for rotating it in a first direction, second drive means connected to said second clutch input shaft for rotating it in a direction counter to said first direction, and means associated with said first and second drive means for permitting rotation of said first drive means in said first direction and of said second drive means in said second direction but preventing said first and second drive means from rotating in any other direction.

2. A recording medium drive comprising first and second spaced reels, record and playback heads situated between said reels, a recording tape extending between and being windable upon each of said reels, a tape drive capstan adjacent one of said heads, means for selectively pressing said tape into driving engagement with said capstan and thereby causing it to be drawn over said heads or for disengaging said tape from said heads and allowing it to slide freely over said capstan, first and second motors having shafts which rotate in opposite directions, one-way overriding clutch means associated with each of said motor shafts for permitting rotation thereof only in the direction which its associated motor tends to rotate it, first and second variable torque clutches connected respectively between said first and second motor shafts and said first and second reels, and first and second means associated with said first and second variable torque clutches for controlling the torque to be connected between said reels and said motor shafts.

3. A recording medium drive as set forth in claim 2 wherein said variable torque clutches are of the hysteresis type and said torque controlling means controls the amount of electrical power applied to said clutches.

4. A recording medium drive as set forth in claim 3 which further comprises means connected to said capstan for rotating it at a selectively variable speed.

5. In a tape transport mechanism having first and second reels and a tape wound about said reels and arranged to engage recording and playback heads, and having means to draw said tape past said heads, the combination of first and second motors having shafts which rotate in different directions, one-way overriding clutch means associated with each of said motor shafts for permitting said motor shafts to rotate only in the direction which its associated motor tends to rotate it, and first and second variable torque clutches, each having an input and an output shaft, said output shafts being respectively connected to said first and second reels and said input shafts being respectively connected to said first and second motor shafts.

6. A tape transport mechanism as set forth in claim 5 wherein said variable torque clutches are of the hysteresis type.

7. A tape transport mechanism as set forth in claim 6 which further includes electrical power control means connected to each of said clutches for controlling the amount of torque to be connected between said input and output shafts.

References Cited UNITED STATES PATENTS 2,607,545 8/1952 McNabb 24255.14 2,718,361 9/1955 Evraets 242--55.11 3,000,583 9/1961 Hoskin 242-55.12 3,109,604 11/1963 Brenner 242-5514 LEONARD D. CHRISTIAN, Primary Examiner. 

